This invention concerns a sleeve joint for joining a driven member on a driving member. More paticularly, the invention is directed to a sleeve joint for driving an impeller on a rotatable shaft.
When driving rotating pump impellers it is often advisable to build in a security device in the joint between the driving shaft and the driven body, which security device is released in case of a sudden stop. This device will diminish the risk of damage to the driving unit and the shaft.
One way of performing this security function is to arrange a driving pin in the joint which will shear upon a sudden stop, letting the shaft rotate freely even when the driven body is stopped. The driving pin is then normally arranged in a hole in the driven body and in a hole in a sleeve on the shaft, the sleeve being driven via a wedge joint positioned in sleeve and shaft. The play between the driven body and the sleeve is then so wide that they are allowed to rotate independently of each other.
This construction often does not work in the expected manner. When the pin has been broken due to the fact the driven body (the impeller) has stopped, the sleeve often splits along the groove, thus eliminating the play between sleeve and the impeller. This means that the driving unit and the driving shaft may be seriously damaged before the electric safety disconnection switch is activated. Frequently the damage resulting is a bent driving shaft.